The present invention relates to temperature changing devices, and, in particular, to portable or disposable beverage coolers which may be activated upon demand by the use of a pressure responsive valve. The disclosed valve is generally applicable in any container, the contents of which is subjected to pressure above or below atmospheric pressure.
As was fully discussed in our two copending applications, the food and beverage industry has been continuously attempting to design an inexpensive, safe, and effective self-contained temperature changing device. Specifically, with regard to the present invention, inventors have been attempting to devise various types of self-contained cooling devices for use in connection with beverage containers, particularly the aluminum can.
There are many beverages that may be stored almost indefinitely at average ambient temperature of 20.degree.-25.degree. C., but that should be cooled immediately before consumption. In general, the cooling of these beverages is accomplished by electrically-run refrigeration units. The use of these units to cool such beverages is not always practical, because refrigerators generally require a source of electricity, they are not usually portable, and they do not cool the beverage quickly.
An alternate method for providing a cooled material on demand is to use portable insulated containers. However, these containers function merely to maintain the previous temperature of the beverage placed inside them, or they require the use of ice cubes to provide the desired cooling effect. When used in conjunction with ice, insulated containers are much more bulky and heavy than he beverage. Moreover, in many locations, ice may not be readily available when the cooling action is required.
Ice cubes have also been used independently to cool beverages rapidly. However, use of ice independently for cooling is often undesirable because ice may be stored only for limited periods above 0.degree. C. Moreover, ice may not be available when the cooling action is desired.
Most attempts to build a self-contained miniaturized cooling device have depended on the use of a refrigerant liquid stored at a pressure above atmospheric pressure, so that the refrigerant vapor could be released directly to the atmosphere. Unfortunately, many available refrigerant liquids for such a system are either flammable, toxic, harmful to the environment, or exist in liquid form at such high pressures that they represent an explosion hazard in quantities suitable for the intended purpose. Conversely, other available refrigerant liquids acceptable for discharge into the atmosphere (such as carbon dioxide) have relatively low heat capacities and latent heats of vaporization. As a result, some cooling devices which release carbon dioxide are more bulky than is commercially acceptable for a portable device.
Our application, Ser. No. 070,973, now U.S. Pat. No. 4,759,191, the contents of which are wholly incorporated herein, discloses the basic concepts underlying the temperature changing device which is used in the present invention. Basically, a cooling effect is produced by the absorption or adsorption of a refrigerant vapor in a chamber separate from the chamber in which the evaporation takes place. In this system, the refrigerant liquid boils under reduced pressure in a sealed chamber and absorbs heat from its surroundings. The vapor generated from the boiling liquid is continuously removed from the first chamber and discharged into a second chamber containing a desiccant or sorbent that absorbs the vapor. Related devices are illustrated in U.S. Pat. No. 4,250,720 to Siegel an Great Britain Patent No. 2,095,386 to Cleghorn, et al.
The prior art discloses numerous disposable beverage containers having various types of self-contained cooling devices therein. For example, see U.S. Pat. Nos. 3,309,890; 3,373,58; 3,494,142; 3,520,148; 3,726,106; and 4,736,599. However, the cooling devices have thus far been unduly complicated and expensive, and consequently no selfcontained refrigeration device has appeared commercially. One reason for the complexity of each of the devices disclosed in the above-cited patents has been the need to construct a mechanism to activate the cooling process upon demand. To accomplish this, the prior art has developed various ways of attaching the cooling device to the fliptop tab portion of the beverage container. Such a construction has compromised the effectiveness of the cooling apparatus a well as has limited the type of cooling devices which can be used. Moreover, the mechanisms take up valuable space within the container so that less beverage can fit within it; alternatively, they require the use of an unduly large container.
It is an object of the present invention to provide a simplified and less expensive method and apparatus for activating a self-contained temperature changing device.
It is another object of the present invention to reduce the complexity of the temperature changing device so that it ay be of a reduced size so that more beverage can be placed inside the container.
It is another object of the present invention to use an improved embodiment of the temperature changing device which will not need to be affixed to any portion of the container so that it may be used in any unmodified industry standard can and in conjunction with all current automated filling equipment.
Other objectives will become apparent from the appended drawing and the following detailed description of the invention.